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Homework
Student Study Guide Homework #3
Back of Study Guide in “Homework” section
Front and back
Homework #4 Handout
Both are due in lab this week
Week 3 Summary
Cranial and spinal nerves
Spinal nerve organization
Dermatomes
Plexuses
Spinal reflex components
Specific reflex types
Stretch reflex
Withdrawal reflex
Crossed extensor reflex
Thought Question’s
1. What are 2 ways to assess whether or not a particular spinal nerve has been damaged?
2. If you cut a dorsal root, what would the result be?
P E R I P H E R A L N E R V E D I S E A S E S
N E R V E R E G E N E R A T I O N
A N S
R E C E P T O R S A N D P H A R M A C O L O G Y
The Nervous System
Peripheral Nerve Regeneration
Possible if cell body has not been damaged
Axon underlying myelin sheath can regenerate
Figure 13.4 (1 of 4)
Endoneurium
Droplets
of myelin
Fragmented
axon
Schwann cells
Site of nerve damage
The axon
becomes
fragmented at
the injury site.
1
Figure 13.4 (2 of 4)
Schwann cell Macrophage Macrophages
clean out the
dead axon distal
to the injury.
2
Figure 13.4 (3 of 4)
Fine axon sprouts
or filaments
Aligning Schwann cells
form regeneration tube
3 Axon sprouts,
or filaments,
grow through a
regeneration tube
formed by
Schwann cells.
Figure 13.4 (4 of 4)
Schwann cell Site of new
myelin sheath
formation
4 The axon
regenerates and
a new myelin
sheath forms.
Single enlarging
axon filament
Neuritis
Inflammation of a nerve
Sciatica
Bell’s Palsy
Shingles
Herpes Zoster virus
Dorsal root ganglia
Consistent with dermatome
Vaccine
Multiple Sclerosis
Loss of myelin in CNS scleroses
Visual disturbances
Muscle weakness
Autoimmune disorder
Remissions
Progressive
Central nervous system (CNS) Peripheral nervous system (PNS)
Motor (efferent) division Sensory (afferent)
division
Somatic nervous
system
Autonomic nervous
system (ANS)
Sympathetic
division
Parasympathetic
division
Figure 14.1
Autonomic Nervous System (ANS)
Involuntary
Visceral reflex system
Sensory (afferent) neurons
Motor (efferent) neurons
Innervate smooth and cardiac muscle and glands
Operate via subconscious control
Skeletal muscle
Cell bodies in central
nervous system Peripheral nervous system Effect
+
+
Effector
organs
ACh
ACh Smooth muscle
(e.g., in gut),
glands, cardiac
muscle
Ganglion
Adrenal medulla Blood vessel
ACh
ACh
ACh
NE
Epinephrine and norepinephrine
Acetylcholine (ACh) Norepinephrine (NE)
Ganglion
Heavily myelinated axon
Lightly myelinated
preganglionic axon
Lightly myelinated preganglionic axons
Neuro-
transmitter
at effector
Unmyelinated
postganglionic
axon
Unmyelinated
postganglionic axon
Stimulatory
Stimulatory
or inhibitory,
depending
on neuro-
transmitter
and
receptors
on effector
organs
Single neuron from CNS to effector organs
Two-neuron chain from CNS to effector organs
SO
MA
TIC
NE
RV
OU
S
SY
ST
EM
AU
TO
NO
MIC
N
ER
VO
US
S
YS
TE
M
PA
RA
SY
MP
AT
HE
TIC
S
YM
PA
TH
ET
IC
Figure 14.2
Figure 14.7
Spinal cord
Dorsal root ganglion
Autonomic ganglion
Stimulus
Response
Visceral sensory
neuron
Integration center • May be preganglionic neuron (as shown) • May be a dorsal horn interneuron • May be within walls of gastrointestinal tract
Sensory receptor
in viscera
2
3
1
5 Visceral effector
Efferent pathway (two-neuron chain) • Preganglionic neuron • Ganglionic neuron
4
ANS Sensory Pathway
Visceral interoceptors (visceroceptors)
Osmolarity
Pressure
Temperature
Blood gases
Chemical composition of plasma and body fluids
ANS Sensory Pathway
Sensory neuron from organ to CNS
Cell body in dorsal root ganglion
Synapse with association neurons
Figure 12.32
Somatic sensory neuron
Dorsal root (sensory)
Dorsal root ganglion
Visceral sensory neuron
Somatic motor neuron
Spinal nerve
Ventral root (motor)
Ventral horn (motor neurons)
Dorsal horn (interneurons)
Visceral motor neuron
Interneurons receiving input from somatic sensory neurons
Interneurons receiving input from visceral sensory neurons
Visceral motor (autonomic) neurons
Somatic motor neurons
ANS Motor Pathway
Two motor neurons between CNS and effector
Preganglionic neuron
Cell body in CNS
Postganglionic neuron
Cell body in autonomic ganglion (outside CNS)
Skeletal muscle
Cell bodies in central
nervous system Peripheral nervous system Effect
+
+
Effector
organs
ACh
ACh Smooth muscle
(e.g., in gut),
glands, cardiac
muscle
Ganglion
Adrenal medulla Blood vessel
ACh
ACh
ACh
NE
Epinephrine and norepinephrine
Acetylcholine (ACh) Norepinephrine (NE)
Ganglion
Heavily myelinated axon
Lightly myelinated
preganglionic axon
Lightly myelinated preganglionic axons
Neuro-
transmitter
at effector
Unmyelinated
postganglionic
axon
Unmyelinated
postganglionic axon
Stimulatory
Stimulatory
or inhibitory,
depending
on neuro-
transmitter
and
receptors
on effector
organs
Single neuron from CNS to effector organs
Two-neuron chain from CNS to effector organs
SO
MA
TIC
NE
RV
OU
S
SY
ST
EM
AU
TO
NO
MIC
N
ER
VO
US
S
YS
TE
M
PA
RA
SY
MP
AT
HE
TIC
S
YM
PA
TH
ET
IC
Figure 14.2
Central nervous system (CNS) Peripheral nervous system (PNS)
Motor (efferent) division Sensory (afferent)
division
Somatic nervous
system
Autonomic nervous
system (ANS)
Sympathetic
division
Parasympathetic
division
Figure 14.1
Divisions at a glance
Sympathetic
“Fight or Flight”
Epinephrine and acetylcholine
Thoracolumbar
Parasympathetic
“Rest and Digest”
Acetylcholine
Craniosacral
Dual Innervation
Salivary glands
Eye
Skin*
Heart
Lungs
Liver and gall- bladder
Genitals
Pancreas
Eye
Lungs
Bladder
Liver and gall- bladder
Pancreas
Stomach
Cervical
Sympathetic ganglia
Cranial
Lumbar
Thoracic
Genitals
Heart
Salivary glands
Stomach
Bladder
Adrenal gland
Parasympathetic Sympathetic
Sacral
Brain stem
L1
T1
Figure 14.3
Dual Innervation
Cranial Outflow
Nerve Ganglia (Terminal Ganglia)
Effector Organ(s)
Oculomotor (III) Ciliary Eye
Facial (VII) Pterygopalatine Submandibular
Salivary, nasal, and lacrimal glands
Glossopharyngeal (IX)
Otic Parotid salivary glands
Vagus (X) Within the walls of target organs
Heart, lungs, and most visceral organs
Sacral
Outflow
S2-S4
Within the walls of target organs
Large intestine, urinary bladder, ureters, and reproductive organs
Parasympathetic Division Outflow
Parasympathetic Division
Neurons leave spinal cord through ventral root
splanchnic nerves inferior hypogastric plexus
terminal ganglia
Pterygopalatine
ganglion
Eye
Lacrimal
gland
Nasal
mucosa
Ciliary
ganglion
Pterygopalatine
ganglion
Submandibular
ganglion Submandibular
and sublingual
glands
CN III
CN VII CN IX CN X
Otic ganglion
Parotid gland
Heart
Lung
Liver and
gallbladder
Stomach
Pancreas
Urinary
bladder
and ureters
Small
intestine
Large
intestine
S2
Pelvic
splanchnic
nerves
Genitalia
(penis,
clitoris, and vagina)
Rectum
Celiac
plexus
Inferior
hypogastric
plexus
Cardiac and
pulmonary
plexuses
S4
Preganglionic
Postganglionic
Cranial nerve
Figure 14.4
Parasympathetic
Division
= Craniosacral
Central nervous system (CNS) Peripheral nervous system (PNS)
Motor (efferent) division Sensory (afferent)
division
Somatic nervous
system
Autonomic nervous
system (ANS)
Sympathetic
division
Parasympathetic
division
Figure 14.1
Figure 14.6
Superior
cervical
ganglion
Middle
cervical
ganglion
Inferior
cervical
ganglion
Sympathetic trunk
(chain) ganglia
Pons
L2
T1
White rami
communicantes
Liver and
gallbladder
Stomach
Spleen
Kidney
Adrenal medulla
Small
intestine
Large
intestine
Genitalia (uterus, vagina, and
penis) and urinary bladder
Celiac ganglion
Inferior
mesenteric
ganglion
Lesser splanchnic nerve
Greater splanchnic nerve
Superior
mesenteric
ganglion
Lumbar
splanchnic
nerves
Eye
Lacrimal gland
Nasal mucosa
Blood vessels;
skin (arrector pili
muscles and
sweat glands)
Salivary glands
Heart
Lung
Rectum
Cardiac and
pulmonary
plexuses
Preganglionic Postganglionic
Sacral
splanchnic
nerves
Sympathetic Division = Thoracolumbar
Sympathetic Division
Preganglionic neurons in T1 – L2
Thoracolumbar division
FYI: Lateral horns
Preganglionic fibers leave through ventral root
ventral rami white rami communicantes
sympathetic trunk (paravertebral) ganglia
Figure 14.5b (1 of 3)
To effector
Blood vessels
Skin (arrector
pili muscles
and sweat
glands)
Dorsal root ganglion
Dorsal ramus of
spinal nerve
Dorsal root
Sympathetic
trunk ganglion
Lateral horn (visceral
motor zone)
Ventral root
Sympathetic trunk
Gray ramus
communicans White ramus
communicans
Ventral ramus of
spinal nerve
Figure 14.5a
Spinal cord
Dorsal root
Ventral root
Sympathetic
trunk ganglion
Sympathetic
trunk
Rib
Ventral ramus
of spinal nerve
Gray ramus
communicans
White ramus
communicans
Thoracic splanchnic nerves
(a) Location of the sympathetic trunk
Sympathetic Trunk Ganglia
Form longitudinal pathways adjacent to vertebral column
Each spinal nerve (except in cervical region)
has an associated ganglion
Figure 14.6
Superior
cervical
ganglion
Middle
cervical
ganglion
Inferior
cervical
ganglion
Sympathetic trunk
(chain) ganglia
Pons
L2
T1
White rami
communicantes
Liver and
gallbladder
Stomach
Spleen
Kidney
Adrenal medulla
Small
intestine
Large
intestine
Genitalia (uterus, vagina, and
penis) and urinary bladder
Celiac ganglion
Inferior
mesenteric
ganglion
Lesser splanchnic nerve
Greater splanchnic nerve
Superior
mesenteric
ganglion
Lumbar
splanchnic
nerves
Eye
Lacrimal gland
Nasal mucosa
Blood vessels;
skin (arrector pili
muscles and
sweat glands)
Salivary glands
Heart
Lung
Rectum
Cardiac and
pulmonary
plexuses
Preganglionic Postganglionic
Sacral
splanchnic
nerves
Sympathetic Division = Thoracolumbar
Sympathetic Trunks and Pathways
Upon entering a sympathetic trunk ganglion a preganglionic fiber may do one of the following:
1. Synapse with a ganglionic neuron within the same ganglion
Figure 14.5b (1 of 3)
To effector
Blood vessels
Skin (arrector
pili muscles
and sweat
glands)
Dorsal root ganglion
Dorsal ramus of
spinal nerve
Dorsal root
Sympathetic
trunk ganglion
Lateral horn (visceral
motor zone)
Ventral root
Sympathetic trunk
Gray ramus
communicans White ramus
communicans
Ventral ramus of
spinal nerve
Synapse at the same level
(b) Three pathways of sympathetic innervation
1
Sympathetic Trunks and Pathways
2. Ascend or descend the sympathetic trunk to synapse in another trunk ganglion
Figure 14.5b (2 of 3)
To effector
Blood vessels
Skin (arrector
pili muscles
and sweat
glands)
Synapse at a higher or lower level
(b) Three pathways of sympathetic innervation
2
Sympathetic Trunks and Pathways
3. Pass through the trunk ganglion and emerge without synapsing
Figure 14.5b (3 of 3)
Splanchnic nerve
Collateral ganglion
(such as the celiac)
Target organ
in abdomen
(e.g., intestine)
Synapse in a distant collateral ganglion
anterior to the vertebral column
(b) Three pathways of sympathetic innervation
3
Figure 14.5a
Spinal cord
Dorsal root
Ventral root
Sympathetic
trunk ganglion
Sympathetic
trunk
Rib
Ventral ramus
of spinal nerve
Gray ramus
communicans
White ramus
communicans
Thoracic splanchnic nerves (a) Location of the sympathetic trunk
Division Origin of
Fibers Length of
Fibers Location
of Ganglia
Sympathetic Thoracolumbar region of the spinal cord
Short preganglionic and long postganglionic
Close to spinal cord
Parasympathetic Brain and sacral spinal cord (craniosacral)
Long preganglionic and short postganglionic
In visceral effector organs
Differences Between the Divisions
Neurotransmitters
Cholinergic fibers release the neurotransmitter ACh
All ANS preganglionic axons
All parasympathetic postganglionic axons
Adrenergic fibers release the neurotransmitter NE
Most sympathetic postganglionic axons
Exceptions: sympathetic postganglionic fibers secrete ACh at sweat glands and some blood vessels in skeletal muscles
Figure 14.2
+
ACh Smooth muscle
(e.g., in gut),
glands, cardiac
muscle
Ganglion
Adrenal medulla Blood vessel
ACh
ACh
ACh
NE
Epinephrine and norepinephrine
Acetylcholine (ACh) Norepinephrine (NE)
Ganglion
Lightly myelinated
preganglionic axon
Lightly myelinated
preganglionic axons
Unmyelinated
postganglionic
axon
Unmyelinated postganglionic axon
Stimulatory
or inhibitory,
depending
on neuro-
transmitter
and
receptors
on effector
organs
Two-neuron chain from CNS to effector organs
AU
TO
NO
MIC
N
ER
VO
US
S
YS
TE
M
PA
RA
SY
MP
AT
HE
TIC
S
YM
PA
TH
ET
IC
Adrenal Medulla
“Sympathomimetic”
Receptors for Neurotransmitters
Cholinergic receptors for ACh
Adrenergic receptors for NE
Cholinergic Receptors
Two types of receptors bind ACh
1. Nicotinic
2. Muscarinic
Named after drugs that bind to them and mimic ACh effects
Remember G-protein linked receptors and second messengers?
Cholinergic Receptors
Nicotinic receptors Blocked with curare
Effect of ACh at nicotinic receptors Always stimulatory
Cholinergic Receptors
Muscarinic
Blocked by atropine
Effect of ACh at muscarinic receptors
Can be either inhibitory or excitatory
Depends on the receptor type of the target organ
Correct 2d. acetylcholine is not always stimulatory. It IS always stimulatory at nicotinic receptors.
Table 14.2
Adrenergic Receptors
Two types
Alpha () (subtypes 1, 2)
Beta () (subtypes 1, 2, 3)
Effects of NE depend on which subclass of receptor predominates on the target organ
Table 14.2
Cardiovascular Pharmacology
Heart
1 - Excitatory in heart
increases heart rate, conduction velocity, and contraction strength
Major blood vessels
2 – Inhibitory
Vasodilation
1 – Excitatory
Vasoconstriction
Cardiovascular Pharmacology
Adrenergic blockers
Used to treat hypertensive disease
blockers - produce vasodilation
1 blockers - decrease heart rate and blood pressure
Table 14.3
Interactions of the Autonomic Divisions
Most visceral organs have dual innervation
Dynamic and precise control of visceral activity
Sympathetic division increases heart and respiratory rates, and inhibits digestion and elimination
Parasympathetic division decreases heart and respiratory rates, and allows for digestion and the discarding of wastes
Salivary glands
Eye
Skin*
Heart
Lungs
Liver and gall- bladder
Genitals
Pancreas
Eye
Lungs
Bladder
Liver and gall- bladder
Pancreas
Stomach
Cervical
Sympathetic ganglia
Cranial
Lumbar
Thoracic
Genitals
Heart
Salivary glands
Stomach
Bladder
Adrenal gland
Parasympathetic Sympathetic
Sacral
Brain stem
L1
T1
Figure 14.3
Questions?